Asalaamu Alaikum, it is very difficult for you as a younger sister to be taken seriously by your brothers as you did mention that they shout at you whenever you try to make them understand. That is why you should instead inform an elder of the family who you think they would take more seriously to try and get them to seek counselling with their wives. This would at least be of some help to your brothers and their relationship with their wives. The elder can advise them that they have nothing to lose but at least try counselling for it is the least they can do to try and save their marriages. You should not play a further role in advising your brothers. What you can do is to send them weekly Islamic reminder texts as well as putting a lecture on the TV whilst they are around.
Apart from that you should be patient and know that you cannot change anything but change can only come from themselves. You getting frustrated and trying to make them understand will not do any good as they will just reject whatever you say. So inform an elder as soon as you can who's advice you know they will be more likely to listen to.
If you ever are in the position to advise your brothers like for example if they ever sharing their feelings with you then in a gentle manner cry to them and share how hurt you and your family are but do not attack them in anyway for this will just make them more defensive. Only do so if they share their feelings with you and it is the right time to tell them how you and your family are affected by their actions and behaviour.
Try to comfort their wives and tell them to have hope. Also tell their wives to try and open up more doors of communication with their husbands even though their husbands may keep some doors of communication closed. The wives should continue to strive to try and share their feelings with their husbands and try and get them to also share their feelings with them so that together they can come up with comprimises and sort out whatever issues they have with each other. Make much dua for your brothers and their wives for Allah to help them with their issues and whatever is best for them will happen.
Concentrate on your own life sister for you will not be accountable for anyone elses life but your own. Invest into the hereafter and do everything to please Allah and nothing to anger or displease him. Rely upon Allah and put your faith and trust in him. Remember him much by doing a lot of Dhikr and recite much Qur'an so that your house may have peace and blessings in it. Get rid of any pictures of animate objects and also play Qur'an recitation as much as you can particularly Surah Baqarah to rid your house of any evil affects.
If you have anymore questions or want help with anything at all then please do not hesitate to ask.
I pray that whatever is best for your brothers and their wives will happen inshallah. Ameen
The following threads and articles wil help you to Maximise the amount of good deeds you do everyday so that you may please Allah and gain high ranks of Paradise inshallah:
10 Steps to Increasing our Iman(Faith)
http://www.islamicboard.com/manners-...man-faith.html (10 Steps to Increasing our Iman(Faith))
30 ways the youth should spend everyday of their lives!
http://www.islamicboard.com/manners-...eir-lives.html (30 ways the youth should spend everyday of their lives!)
Easy Dhikr which is light on the tongue but heavy on the scales!
http://www.islamicboard.com/manners-...vy-scales.html (Easy Dhikr which is light on the tongue but heavy on the scales!)
My Daily Ibadah (worship) check!
http://www.islamicboard.com/manners-...hip-check.html (My Daily Ibadah (worship) check!)
10 steps to getting closer to Allah
http://www.islamicboard.com/manners-...ser-allah.html (10 steps to getting closer to Allah)
Forty Very Easy, Quick & Rewarding Good Deeds for all of us to do Everyday!
http://www.islamicboard.com/worship-...-everyday.html (Forty Very Easy, Quick & Rewarding Good Deeds for all of us to do Everyday!)
VERY Rewarding Nafl Salaahs we can Pray Everyday!
http://www.islamicboard.com/worship-...-everyday.html (VERY Rewarding Nafl Salaahs we can Pray Everyday!)
Wasting Time is worse than Death!
http://www.islamicboard.com/general/...han-death.html
The Effects of Good deeds will remain forever!!!
http://www.islamicboard.com/general/...n-forever.html
Want to see the REAL appearance of Almighty Allah everyday?
http://www.islamicboard.com/general/...-everyday.html
12 Ways We Can Maximise Our Worship Each Day
http://www.islamicboard.com/manners-...-each-day.html
Here are some very beneficial lectures to increase your imaan and fear of Allah:
AMAZING short speech -"The Goodly Life"
http://www.youtube.com/watch?v=-fugf1DcNyc
Remembrance: ask Allah for his forgiveness
http://www.youtube.com/watch?v=Z-EK9r3rMzQ
Angel of Death!!! - Sheikh Ahmed Ali
http://www.youtube.com/watch?v=tUzRJXlB2uA
HARD HITTING Lecture on HELLFIRE & the Day of JUDGEMENT! يوم القيامة والجحيم
http://www.youtube.com/watch?v=0O6L_fBk7VM
Sheikh Ahmad Ali - Hellfire Talk Part 1/3
http://www.youtube.com/watch?v=DWTehIeCOUU
Sheikh Ahmad Ali - Hellfire Talk Part 2/3
http://www.youtube.com/watch?v=yXTtk7rWx_U
Sheikh Ahmad Ali - Hellfire Talk Part 3/3
http://www.youtube.com/watch?v=wmiD86w9fBc
Islam - Punishment of the Grave by Sheikh Riyadh ul Haq
http://www.youtube.com/watch?v=UWb-hYIm2WE
Death and the Grave by Murtaza Khan
http://www.youtube.com/watch?v=7r2nzJVecqo
How can we not appreciate what we have after watching this?
http://www.youtube.com/watch?v=AkEBUC0APMg
And Allah knows best in all matters